Laminates comprising reinforced aerogel composites

ABSTRACT

Described herein are aerogel composites. The aerogel composites comprise at least one base layer having a top surface and a bottom surface, the base layer comprising a reinforced aerogel composition which comprises a reinforcement material and a monolithic aerogel framework, a first facing layer comprising a first facing material attached to the top surface of the base layer, and a second facing layer comprising a second facing material attached to the bottom surface of the base layer. At least a portion of the monolithic aerogel framework of the base layer extends into at least a portion of both the first facing layer and the second facing layer. The first facing material and the second facing material each consist essentially of fluoropolymer material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/287,762 filed on Jan. 27, 2016, which is incorporated herein byreference in its entirety.

BACKGROUND

Low-density aerogel materials are widely considered to be the best solidinsulators available. Aerogels function as insulators primarily byminimizing conduction (low structural density results in tortuous pathfor energy transfer through the solid framework), convection (large porevolumes and very small pore sizes result in minimal convection), andradiation (IR absorbing or scattering dopants are readily dispersedthroughout the aerogel matrix). Aerogels can be used in a broad range ofapplications, including: heating and cooling insulation, acousticsinsulation, electronic dielectrics, aerospace, energy storage andproduction, and filtration. Furthermore, aerogel materials display manyother interesting acoustic, optical, mechanical, and chemical propertiesthat make them abundantly useful in various insulation andnon-insulation applications.

SUMMARY OF THE INVENTION

In one general aspect, the present disclosure can provide an aerogelmaterial or composition which is durable and easy to handle. In oneembodiment, the aerogel composition is a reinforced aerogel compositionthat is flexible, resilient, and self-supporting. In one embodiment, theaerogel composition is a foam-reinforced aerogel composition that isflexible, resilient, and self-supporting. In one embodiment, the aerogelcomposition is a foam-reinforced aerogel composition which is laminatedwith at least one face sheet, wherein the resulting laminated compositeis flexible, resilient, and self-supporting.

In one general aspect, the present disclosure can provide an aerogelcomposite comprising: at least one base layer comprising a reinforcedaerogel composition, wherein the reinforced aerogel compositioncomprises a reinforcement material and an aerogel framework, and whereinthe base layer has a top surface and a bottom surface; and at least onefacing layer attached to at least one surface of the base layer. In oneembodiment, at least a portion of the aerogel framework of the baselayer extends into at least a portion of the aerogel framework of thefacing layer. In one embodiment, the facing layer comprises an aerogelframework integrated within the facing material; and at least a portionof the aerogel framework of the base layer is continuous with at least aportion of the aerogel framework of the facing layer.

In one general aspect, the present disclosure can provide an aerogelcomposite comprising: at least one base layer comprising a reinforcedaerogel composition, wherein the reinforced aerogel compositioncomprises a reinforcement material and an aerogel framework, and whereinthe base layer has a top surface and a bottom surface; and at least onefacing layer attached to the top surface of the base layer and at leastone facing layer attached to the bottom surface of the base layer. Inone embodiment, at least a portion of the aerogel framework of the baselayer extends into at least a portion of both the top facing layer andthe bottom facing layer. In one embodiment, both the top facing layerand the bottom facing layer comprise an aerogel framework integratedwithin the facing material; and at least a portion of the aerogelframework of the base layer is continuous with at least a portion of theaerogel framework of both the top facing layer and the bottom facinglayer.

In one general aspect, the present disclosure can provide a method ofpreparing an aerogel composite, comprising: providing a base layercomprising a reinforcement material and an aerogel framework, whereinthe base layer has a top surface and a bottom surface; providing afacing layer comprising a sheet of facing material; and attaching thefacing layer to a surface of the base layer. In one embodiment, themethod comprises providing at least two facing layers comprising sheetsof facing material; attaching a facing layer to the top surface of thebase layer; and attaching a facing layer to the bottom surface of thebase layer.

In one general aspect, the present disclosure can provide a method ofpreparing an aerogel composite, comprising: providing a base layercomprising a reinforcement material, wherein the base layer has a topsurface and a bottom surface; providing a facing layer comprising asheet of facing material; attaching the facing layer to a surface of thebase layer; providing a gel precursor solution comprising gel precursormaterials and a solvent; contacting the precursor solution with thefacing layer, and allowing at least a portion of the gel precursorsolution to pass through the facing layer into the reinforcementmaterial of the base layer; allowing the gel precursor materials in theprecursor solution to transition into a gel composition, forming areinforced gel sheet; and extracting at least a portion of the solventfrom the reinforced gel sheet to obtain a reinforced aerogel composite.In one embodiment, the method comprises providing at least two facinglayers comprising a sheet of facing material; attaching a facing layerto the top surface of the base layer and attaching a facing layer to thebottom surface of the base layer; providing a gel precursor solutioncomprising gel precursor materials and a solvent; contacting theprecursor solution with the top facing layer; allowing at least aportion of the gel precursor solution to pass through the top facinglayer into the reinforcement material of the base layer; and allowing atleast a portion of the gel precursor solution to pass through the topfacing layer and through the base layer into the bottom facing layer.

In one embodiment, the step of attaching the facing layer to a surfaceof the base layer produces a laminate sheet of reinforcement material;and the laminate sheet of reinforcement material is dispensed onto amoving element prior to dispensing the precursor solution onto thefacing layer of the laminate sheet. In one embodiment, the step ofattaching the facing layer to a surface of the base layer produces alaminate sheet of reinforcement material; and the laminate sheet ofreinforcement material is rolled into a preform roll and placed in acontainer prior to dispensing the precursor solution onto the facinglayer of the laminate sheet with the container.

In one embodiment, the reinforcement material is a foam reinforcementmaterial. In one embodiment, the reinforcement material is an open-cellfoam reinforcement material, including a reticulated open-cell foamreinforcement material. In one embodiment, the foam reinforcementmaterial comprises polyurethane foam or melamine foam. In oneembodiment, the reinforced aerogel composite has a density of 0.250 g/ccor less, 0.230 g/cc or less, 0.200 g/cc or less, 0.160 g/cc or less,0.180 g/cc or less, between 0.140 g/cc and 0.250 g/cc, or between 0.160g/cc and 0.250 g/cc. In one embodiment, the reinforced aerogel compositehas a thermal conductivity of 26.0 mW/m-K or less; 24.0 mW/m-K or less;22.0 mW/m-K or less; 20.0 mW/m-K or less; 19.0 mW/m-K or less; between12.0 mW/m-K and 26.0 mW/m-K, between 14.0 mW/m-K and 26.0 mW/m-K,between 16.0 mW/m-K and 26.0 mW/m-K, or between 18.0 mW/m-K and 26.0mW/m-K.

In one embodiment, the facing layer comprises a polymeric sheet; morespecifically a polymeric sheet which comprises polyesters,polyethylenes, polyurethanes, polypropylenes, polyacrylonitriles,polyamids, aramids; and more specifically polymers such aspolyethyleneterphthalate, low density polyethylene, ethylene-propyleneco-polymers, poly(4-methyl-pentane), polytetrafluoroethylene,poly(1-butene), polystyrene, polyvinylacetatae, polyvinylchloride,polyvinylidenechloride, polyvinylfluoride, polyvinylacrylonitrile,polymethylmethacrylate, polyoxymethylene, polyphenylenesulfone,cellulosetriacetate, polycarbonate, polyethylene naphthalate,polycaprolactam, polyhexamethyleneadipamide, polyundecanoamide,polyimide, or combinations thereof. In one embodiment, the polymericsheet comprises or consists essentially of an expanded polymericmaterial; more specifically an expanded polymeric material comprisingPTFE (ePTFE), expanded polypropylene (ePP), expanded polyethylene (ePE),expanded polystyrene (ePS), or combinations thereof. In one embodiment,the polymeric sheet comprises or consists essentially of a microporouspolymeric material characterized by a pore size ranging from 0.1 μm to210 μm, 0.1 μm to 115 μm, 0.1 μm to 15 μm, or 0.1 μm to 0.6 μm.

In one embodiment, the facing layer material comprises or consistsessentially of a fluoropolymeric material; more specifically afluoropolymeric material comprising polytetrafluoroethylene (PTFE);microporous PTFE described in U.S. Pat. No. 5,814,405; expanded PTFE(ePTFE) such as Gore-Tex® (available from W.L. Gore); polyvinylfluoride(PVF); polyvinylidene fluoride (PVDF); perfluoroalkoxy (PFA);fluorinated ethylene-propylene (FEP); Polychlorotrifluoroethylene(PCTFE); Ethylene tetrafluoroethylene (ETFE); polyvinylidene fluoride(PVDF); ethylene chlorotrifluoroethylene (ECTFE); or combinationsthereof.

In one embodiment, the facing layer material comprises or consistsessentially of a non-fluoropolymeric material; more specifically anon-fluoropolymeric material comprising aluminized Mylar; low densitypolyethylene, such as Tyvek® (available from DuPont); rubber or rubbercomposites; elastic fibers such as spandex, nylon, lycra or elastane; orcombinations thereof. In one embodiment, the facing material is aflexible facing material. In one embodiment, the facing material is madeof elastic fibers comprising spandex, nylon, lycra, elastane, orcombinations thereof. In one embodiment, the facing material is afluid-permeable facing material.

In one embodiment, the facing layer is attached to the base layer by anadhesive or a non-adhesive mechanism. In one embodiment, the adhesivecomprises an aerosol adhesive, a urethane-based adhesive, an acrylateadhesive, a hot melt adhesive, an epoxy, a rubber resin adhesive, or apolyurethane composite adhesive. In one embodiment, the non-adhesivemechanism comprises stitching, sealing bags, rivets, buttons, clamps,wraps, or braces.

In one general aspect, the present disclosure can provide a method ofpreparing an aerogel composition, comprising the steps of: providing ablock of a reinforced aerogel comprising a foam reinforcement material;exposing the block of a reinforced aerogel to a skiving or lathe-peelingapparatus; allowing the skiving or lathe-peeling apparatus to remove acontinuous sheet of reinforced aerogel material from the block ofreinforced aerogel, thereby producing a sheet of reinforced aerogel.

In one general aspect, the present disclosure can provide a method ofpreparing an aerogel composition, comprising the steps of: placingwithin a container multiple pieces of a reinforced aerogel comprising afoam reinforcement material; providing a precursor solution comprisinggel precursor materials and a solvent; dispensing the gel precursorsolution into the container and allowing the gel precursor to infiltratethe pieces of foam reinforcement material within the container; allowingthe gel precursor materials in the precursor solution to transition intoa gel composition, forming a block of reinforced gel material; exposingthe block of a reinforced gel material to a skiving or lathe-peelingapparatus; allowing the skiving or lathe-peeling apparatus to remove acontinuous sheet of reinforced gel material from the block of reinforcedgel material, thereby producing a sheet of reinforced gel; andextracting at least a portion of the solvent from the sheet ofreinforced gel material to obtain a sheet of reinforced aerogelmaterial.

In one general aspect, the present disclosure can provide a method ofpreparing an aerogel composition, comprising the steps of: placingwithin a container multiple pieces of a reinforced aerogel comprising afoam reinforcement material; providing a precursor solution comprisinggel precursor materials and a solvent; dispensing the gel precursorsolution into the container and allowing the gel precursor to infiltratethe pieces of foam reinforcement material within the container; allowingthe gel precursor materials in the precursor solution to transition intoa gel composition, forming a block of reinforced gel material;extracting at least a portion of the solvent from the block ofreinforced gel material to obtain a block of reinforced aerogelmaterial; exposing the block of a reinforced aerogel material to askiving or lathe-peeling apparatus; and allowing the skiving orlathe-peeling apparatus to remove a continuous sheet of reinforcedaerogel material from the block of reinforced aerogel material, therebyproducing a sheet of reinforced aerogel material.

In one general aspect, the present disclosure can provide a method ofpreparing an aerogel composition, comprising the steps of: providing asheet of reinforced aerogel material comprising a foam reinforcementmaterial; heating the sheet of reinforced aerogel material to a targettemperature; molding or shaping the sheet of reinforced aerogel materialbefore, during, or after the heating step; and allowing the molded orshaped sheet of reinforced aerogel material to cool, such that the sheetof reinforced aerogel material maintains the molded shape after cooling.In one embodiment, the target temperature is between 50° C. and 200° C.,between 75° C. and 200° C., between 100° C. and 175° C., between 120° C.and 160° C., or about 150° C. In one embodiment, the target temperatureis a temperature above the softening point of the foam reinforcementmaterial and below the maximum use temperature of the foam reinforcementmaterial.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a method of preparing reinforced gel sheets from aerogelprecursors and reinforcement sheets, using a conveyor system.

FIG. 2 depicts a method of preparing reinforced gel sheets from aerogelprecursors and reinforcement sheets, using a gel-in-a-roll system.

FIG. 3 depicts a flat laminate sheet comprising a base layer comprisinga foam-reinforced aerogel composite with flexible facing layers on eachsurface of the base layer.

FIG. 4 depicts a rolled laminate sheet comprising a base layercomprising a foam-reinforced aerogel composite with flexible facinglayers on each surface of the base layer.

FIG. 5 depicts a laminate sheet comprising a base layer comprising afoam-reinforced aerogel composite with flexible, impermeable facinglayers on each surface of the base layer.

FIG. 6 depicts a rolled laminate sheet comprising layers which arebonded using ultrasonic sewing.

FIG. 7 depicts a flat laminate sheet comprising layers which are bondedusing ultrasonic sewing.

FIG. 8 depicts a flat foam-reinforced aerogel sheet which is folded intoa pre-form shape, and secured with a band.

FIG. 9 depicts a foam-reinforced aerogel sheet which was shaped from aflat sheet into a curved pre-form shape using heat treatment.

FIG. 10 depicts a multilayer laminate comprising multiple layers offoam-reinforced aerogel sheets which were shaped from a flat sheet intoa curved pre-form shape using heat treatment, and then laminatedtogether using an adhesive.

FIG. 11 depicts a pipe insulation section comprising multiple layers offoam-reinforced aerogel sheets which were shaped from a flat sheet intoa curved pre-form shape using heat treatment, then laminated togetherusing an adhesive, and finally secured around a pipe section.

DETAILED DESCRIPTION

Aerogels are a class of porous materials with open-cells comprising aframework of interconnected structures, with a corresponding network ofpores integrated within the framework, and an interstitial phase withinthe network of pores which is primarily comprised of gases such as air.Aerogels are typically characterized by a low density, a high porosity,a large surface area, and small pore sizes. Aerogels can bedistinguished from other porous materials by their physical andstructural properties.

Aerogels can also be extremely brittle and difficult to handle. Thebrittleness of low density aerogels can present significantcomplications during production and processing, which can significantlylimit large scale manufacturing of these materials. The brittleness ofaerogels can also make the instillation and application of aerogelmaterials difficult, due to dusting, cracking or structural degradationconcerns. A need therefore exists for the development of aerogelcompositions which are flexible, durable and easy to handle.

One solution to the brittleness of low density aerogels is to produceaerogel materials which are reinforced with a more rigid or resilientmaterial. These reinforcing materials can include polymeric binders,adhesive glues, fibers or fibrous mats, sealed envelopes, cements, andfoams. However, many reinforced composite aerogels suffer fromsignificantly degraded thermal insulation performance when compared tothe aerogel monolith alone. Reinforced composite aerogels can also havepoor stability in wet or high temperature conditions, as well asinsufficient flexibility for many uses. Many reinforcing materials failto fully resolve issues related to dusting, cracking or structuraldegradation of aerogel materials. Furthermore, reinforcing materials canoften be expensive and difficult to acquire, presenting significantcomplications and disadvantages during large-scale manufacturing andmarketing operations for commercial products.

A need therefore exists for the development of reinforced aerogelcompositions which are flexible, durable, easy to handle, and resistantto dusting, cracking and general structural degradation. A need alsoexists for the development of reinforced aerogel compositions which areinexpensive, which can be easily produced through large-scalemanufacturing, and which can be effectively applied in a broad spectrumof insulation applications.

Within the context of the present disclosure, the term “aerogel” or“aerogel material” refers to a gel comprising a framework ofinterconnected structures, with a corresponding network ofinterconnected pores integrated within the framework, and containinggases such as air as a dispersed interstitial medium; and which ischaracterized by the following physical and structural properties(according to Nitrogen Porosimetry Testing) attributable to aerogels:(a) an average pore diameter ranging from about 2 nm to about 100 nm,(b) a porosity of at least 80% or more, and (c) a surface area of about20 m²/g or more.

Aerogel materials of the present disclosure thus include any aerogels orother open-celled compounds which satisfy the defining elements setforth in previous paragraphs; including compounds which can be otherwisecategorized as xerogels, cryogels, ambigels, microporous materials, andthe like.

Aerogel materials may also be further characterized by additionalphysical properties, including: (d) a pore volume of about 2.0 mL/g ormore, preferably about 3.0 mL/g or more; (e) a density of about 0.50g/cc or less, preferably about 0.25 g/cc or less; and (f) at least 50%of the total pore volume comprising pores having a pore diameter ofbetween 2 and 50 nm; though satisfaction of these additional propertiesis not required for the characterization of a compound as an aerogelmaterial.

Within the context of the present disclosure, the term “innovativeprocessing and extraction techniques” refers to methods of replacing aliquid interstitial phase in a wet-gel material with a gas such as air,in a manner which causes low pore collapse and low shrinkage to theframework structure of the gel. Drying techniques, such as ambientpressure evaporation, often introduce strong capillary pressures andother mass transfer limitations at the liquid-vapor interface of theinterstitial phase being evaporated or removed. The strong capillaryforces generated by liquid evaporation or removal can cause significantpore shrinkage and framework collapse within the gel material. The useof innovative processing and extraction techniques during the extractionof a liquid interstitial phase reduces the negative effects of capillaryforces on the pores and the framework of a gel during liquid phaseextraction.

In certain embodiments, an innovative processing and extractiontechnique uses near critical or super critical fluids, or near criticalor super critical conditions, to extract the liquid interstitial phasefrom a wet-gel material. This can be accomplished by removing the liquidinterstitial phase from the gel near or above the critical point of theliquid or mixture of liquids. Co-solvents and solvent exchanges can beused to optimize the near critical or super critical fluid extractionprocess.

Within the context of the present disclosure, the terms “framework” or“framework structure” refer to the network of interconnected oligomers,polymers or colloidal particles that form the solid structure of a gelor an aerogel. The polymers or particles that make up the frameworkstructures typically have a diameter of about 100 angstroms. However,framework structures of the present disclosure can also include networksof interconnected oligomers, polymers or colloidal particles of alldiameter sizes that form the solid structure within in a gel or aerogel.Furthermore, the terms “silica-based aerogel” or “silica-basedframework” refer to an aerogel framework in which silica comprises atleast 50% (by weight) of the oligomers, polymers or colloidal particlesthat form the solid framework structure within in the gel or aerogel.

Within the context of the present disclosure, the term “aerogelcomposition” refers to any composite material which includes aerogelmaterial as a component of the composite. Examples of aerogelcompositions include, but are not limited to: fiber-reinforced aerogelcomposites; aerogel composites which include additive elements such asopacifiers; aerogel-foam composites; aerogel-polymer composites; andcomposite materials which incorporate aerogel particulates, particles,granules, beads, or powders into a solid or semi-solid material, such asbinders, resins, cements, foams, polymers, or similar solid materials.

Within the context of the present invention, the term “foam” refers to amaterial comprising a framework of interconnected polymeric structures,with a corresponding network of interconnected pores or collection ofindependent pores integrated within the framework, and containing gasessuch as air as a dispersed medium within the pores of the foam; andwhich has an average pore diameter above 300 nm.

Alternatively, the term “foam” can refer to a material comprising aporous solid formed by a dispersion in which a large proportion of gasby volume is dispersed in the form of gas bubbles into a liquid, solidor gel, wherein the gas bubbles are often stabilized by solid particlesor by soluble substances. In general, foams can be made using a widevariety of processes—see, for example, U.S. Pat. Nos. 6,147,134;5,889,071; 6,187,831; and 5,229,429.

The pores within the foam framework can also be referred to as “cells”.Cells can be divided by cell walls or membranes, creating a collectionof independent closed pores within the foam. The term “closed cell foam”refers to foam materials in which at least 50% of the pore volume isconfined cells enclosed by membranes or walls. Cells in the foam canalso be interconnected through cell openings, creating a network ofinterconnected open pores within the foam. The term “open cell foam”refers to foam materials in which at least 50% of the pore volume isopen cells. The open-cell foam can comprise a reticulated open-cellfoam, a non-reticulated open-cell foam, or a combination thereof.Reticulated foams are open cell foams which are produced through areticulation process which eliminates or punctures cell membranes withinthe foam material. Reticulated foams typically have a higherconcentration of open cells than non-reticulated foams, but tend to bemore expensive and difficult to produce. Generally, no foam material hasentirely one type of cell structure (open cell or close cell). Foams canbe made using a wide variety of processes, including foam productionprocesses presented in U.S. Pat. Nos. 6,147,134, 5,889,071, 6,187,831,5,229,429, 4,454,248, and US Patent Application No 20070213417.

Within the context of the present invention, the term “rebonded foam”refers to a foam that results from a process of adhering together acollection of particles or pieces of foam material (often manufacturingscrap). Various adhesives and bonding processes may be used, and thefoam used may be ground or shredded prior to rebonding. Foam may berebonded as a way to lower cost through the use of foam that wouldotherwise be waste. A typical application for rebonded foam is as carpetunderlay.

Within the context of the present invention, the term “monolithic”refers to aerogel materials in which a majority (by weight) of theaerogel included in the aerogel material or composition is in the formof a unitary interconnected aerogel nanostructure. Monolithic aerogelmaterials include aerogel materials which are initially formed to have aunitary interconnected gel or aerogel nanostructure, but which aresubsequently cracked, fractured or segmented into non-unitary aerogelnanostructures. Monolithic aerogel materials are differentiated fromparticulate aerogel materials. The term “particulate aerogel material”refers to aerogel materials in which a majority (by weight) of theaerogel included in the aerogel material is in the form of particulates,particles, granules, beads, or powders, which can be combined orcompressed together but which lack an interconnected aerogelnanostructure between individual particles.

Within the context of the present invention, the term “reinforcedaerogel composition” refers to aerogel compositions which comprise areinforcing phase within the aerogel material which is not part of theaerogel framework. The reinforcing phase can be any material whichprovides increased flexibility, resilience, conformability or structuralstability to the aerogel material. Examples of well-known reinforcingmaterials include, but are not limited to: open-cell foam reinforcementmaterials, polymeric reinforcement materials, and fiber reinforcementmaterials such as discrete fibers, woven materials, non-woven materials,battings, webs, mats, and felts. Additionally, fiber basedreinforcements may be combined with one or more of the other reinforcingmaterials, and can be oriented continuously throughout or in limitedpreferred parts of the composition.

Within the context of the present invention, the term “fiber-reinforcedaerogel composition” refers to a reinforced aerogel composition whichcomprises a fiber reinforcement material as a reinforcing phase.Examples of fiber reinforcement materials include, but are not limitedto, discrete fibers, woven materials, non-woven materials, battings,webs, mats, felts, or combinations thereof. Fiber reinforcementmaterials can comprise a range of materials, including, but not limitedto: Polyesters, polyolefin terephthalates, poly(ethylene) naphthalate,polycarbonates (examples Rayon, Nylon), cotton, (e.g. lycra manufacturedby DuPont), carbon (e.g. graphite), polyacrylonitriles (PAN), oxidizedPAN, uncarbonized heat treated PANs (such as those manufactured by SGLcarbon), fiberglass based material (like S-glass, 901 glass, 902 glass,475 glass, E-glass,) silica based fibers like quartz, (e.g. Quartzelmanufactured by Saint-Gobain), Q-felt (manufactured by Johns Manville),Saffil (manufactured by Saffil), Durablanket (manufactured by Unifrax)and other silica fibers, Duraback (manufactured by Carborundum),Polyaramid fibers like Kevlar, Nomex, Sontera (all manufactured byDuPont), Conex (manufactured by Taijin), polyolefins like Tyvek(manufactured by DuPont), Dyneema (manufactured by DSM), Spectra(manufactured by Honeywell), other polypropylene fibers like Typar,Xavan (both manufactured by DuPont), fluoropolymers like PTFE with tradenames as Teflon (manufactured by DuPont), Goretex (manufactured by W.L.GORE), Silicon carbide fibers like Nicalon (manufactured by COICeramics), ceramic fibers like Nextel (manufactured by 3M), Acrylicpolymers, fibers of wool, silk, hemp, leather, suede, PBO-Zylon fibers(manufactured by Tyobo), Liquid crystal material like Vectan(manufactured by Hoechst), Cambrelle fiber (manufactured by DuPont),Polyurethanes, polyamaides, Wood fibers, Boron, Aluminum, Iron,Stainless Steel fibers and other thermoplastics like PEEK, PES, PEI,PEK, PPS.

Within the context of the present invention, the terms “foam-reinforcedaerogel composition” or “aerogel-foam composite” refer to a reinforcedaerogel composition which comprises a foam reinforcement material as areinforcing phase. The foam reinforcement material can comprise an opencell foam, a closed cell foam, or a combination thereof. Suitable foamsfor use in the present invention include, but are not limited to, foamsmade from polymeric materials. Examples include foams made frompolyolefins, polyurethanes, phenolics, melamine, cellulose acetate, andpolystyrene. Polyolefin foams are preferred; more preferred arepolyurethane foams. Polyether polyurethane foams are preferred fornon-reticulated foams; polyester polyurethane foams are preferred forreticulated foams. Examples of polyurethane and polyepoxide foams foruse in the present invention are presented in U.S. Pat. Nos. 2,117,605,3,094,433, 2,739,134, 3,112,524, 2,789,095, 3,129,191, 2,811,499,3,171,820, 2,831,820, 2,920,983, 3,342,922, 2,926,390, 3,386,877,2,936,294, 3,459,274, 2,993,869, 3,504,064, 3,025,200, 3,506,600,3,055,360, 3,650,993, 3,057,750, 3,860,537, 3,060,137, 4,252,517,3,075,926, 3,082,611 and 3,090,094. Melamine foams are also preferred incertain embodiments. Examples of melamine foams for use in the presentinvention are presented in U.S. Pat. Nos. 8,546,457, 4,666,948, and WO2001/094436. The foam reinforcement material can be a rebonded foam.

Within the context of the present disclosure, the terms “aerogelblanket” or “aerogel blanket composition” refer to aerogel compositionsreinforced with a continuous sheet of reinforcement material. Aerogelblanket compositions can be differentiated from other reinforced aerogelcomposition which are reinforced with a non-continuous fiber or foamnetwork, such as separated agglomerates or clumps of fiber materials.Aerogel blanket compositions are particularly useful for applicationsrequiring flexibility, since they are highly conformable and can be usedlike a blanket to cover surfaces of simple or complex geometry, whilealso retaining the excellent thermal insulation properties of aerogels.Aerogel blanket compositions and similar fiber-reinforced aerogelcompositions are described in Published US patent application2002/0094426 (paragraphs 12-16, 25-27, 38-58, 60-88), which is herebyincorporated by reference according to the individually cited sectionsand paragraphs.

Within the context of the present invention, the term “wet gel” refersto a gel in which the mobile interstitial phase within the network ofinterconnected pores is primarily comprised of a liquid phase such as aconventional solvent, liquefied gases such as liquid carbon dioxide, ora combination thereof. Aerogels typically require the initial productionof a wet gel, followed by innovative processing and extraction toreplace the mobile interstitial liquid phase in the wet gel with air toform a dry gel. Examples of wet gels include, but are not limited to:alcogels, hydrogels, ketogels, carbonogels, and any other wet gels knownto those in the art.

Within the context of the present invention, the terms “additive” or“additive element” refer to materials which can be added to an aerogelcomposition before, during, or after the production of the aerogel.Additives can be added to alter or improve desirable properties in anaerogel, or to counteract undesirable properties in an aerogel.Additives are typically added to an aerogel material either prior orduring gelation. Examples of additives include, but are not limited to:microfibers, fillers, reinforcing agents, stabilizers, thickeners,elastic compounds, opacifiers, coloring or pigmentation compounds,radiation absorbing compounds, radiation reflecting compounds, corrosioninhibitors, thermally conductive components, phase change materials, pHadjustors, redox adjustors, HCN mitigators, off-gas mitigators,electrically conductive compounds, electrically dielectric compounds,magnetic compounds, radar blocking components, hardeners, anti-shrinkingagents, and other aerogel additives known to those in the art. Otherexamples of additives include smoke suppressants and fire suppressants.Published US Pat. App. 20070272902 A1 (Paragraphs [0008] and[0010]-[0039]) includes teachings of smoke suppressants and firesuppressants, and is hereby incorporated by reference according to theindividually cited paragraphs.

Within the context of the present disclosure, the terms “flexible” and“flexibility” refer to the ability of an aerogel material or compositionto be bent or flexed without macrostructural failure. Preferably,aerogel compositions of the present disclosure are capable of bending atleast 5°, at least 25°, at least 45°, at least 65°, or at least 85°without macroscopic failure; and/or have a bending radius of less than 4feet, less than 2 feet, less than 1 foot, less than 6 inches, less than3 inches, less than 2 inches, less than 1 inch, or less than ½ inchwithout macroscopic failure. Likewise, the terms “highly flexible” or“high flexibility” refer to aerogel materials or compositions capable ofbending to at least 90° and/or have a bending radius of less than ½ inchwithout macroscopic failure. Furthermore, the terms “classifiedflexible” and “classified as flexible” refer to aerogel materials orcompositions which can be classified as flexible according to ASTMclassification standard C1101 (ASTM International, West Conshohocken,Pa.).

Aerogel materials or compositions of the present invention can beflexible, highly flexible, and/or classified flexible. Aerogel materialsor compositions of the present invention can also be drapable. Withinthe context of the present invention, the terms “drapable” and“drapability” refer to the ability of an aerogel material or compositionto be bent or flexed to 90° or more with a radius of curvature of about4 inches or less, without macroscopic failure. An aerogel material orcomposition of the present invention is preferably flexible such thatthe composition is non-rigid and may be applied and conformed tothree-dimensional surfaces or objects, or pre-formed into a variety ofshapes and configurations to simplify installation or application.

Within the context of the present disclosure, the terms “resilient” and“resilience” refer to the ability of an aerogel material or compositionto at least partially return to an original form or dimension followingdeformation through compression, flexing, or bending. Resilience may becomplete or partial, and it may be expressed in terms of percentagereturn. An aerogel material or composition of the present disclosurepreferably has a resilience of more than 25%, more than 50%, more than60%, more than 70%, more than 75%, more than 80%, more than 85%, morethan 90%, or more than 95% return to an original form or dimensionfollowing a deformation. Likewise, the terms “classified resilient” and“classified as resilient” refer to aerogel materials or compositions ofthe present disclosure which can be classified as resilient flexibleaccording to ASTM classification standard C1101 (ASTM International,West Conshohocken, Pa.).

Within the context of the present disclosure, the term “self-supporting”refers to the ability of an aerogel material or composition to beflexible and/or resilient based primarily on the physical properties ofthe aerogel and any reinforcing phase in the aerogel composition.Self-supporting aerogel materials or compositions of the presentdisclosure can be differentiated from other aerogel materials, such ascoatings, which rely on an underlying substrate to provide flexibilityand/or resilience to the material.

Within the context of the present disclosure, the term “shrinkage”refers to the ratio of: 1) the difference between the measured finaldensity of the dried aerogel material or composition and the targetdensity calculated from solid content in the sol-gel precursor solution,relative to 2) the target density calculated from solid content in thesol-gel precursor solution. Shrinkage can be calculated by the followingequation: Shrinkage=[Final Density (g/cm³)−Target Density(g/cm³)]/[Target Density (g/cm³)]. Preferably, shrinkage of an aerogelmaterial of the present disclosure is preferably 50% or less, 25% orless, 10% or less, 8% or less, 6% or less, 5% or less, 4% or less, 3% orless, 2% or less, 1% or less, 0.1% or less, about 0.01% or less, or in arange between any two of these values.

Within the context of the present disclosure, the terms “thermalconductivity” and “TC” refer to a measurement of the ability of amaterial or composition to transfer heat between two surfaces on eitherside of the material or composition, with a temperature differencebetween the two surfaces. Thermal conductivity is specifically measuredas the heat energy transferred per unit time and per unit surface area,divided by the temperature difference. It is typically recorded in SIunits as mW/m*K (milliwatts per meter*Kelvin). The thermal conductivityof a material may be determined by methods known in the art, including,but not limited to: Test Method for Steady-State Thermal TransmissionProperties by Means of the Heat Flow Meter Apparatus (ASTM C518, ASTMInternational, West Conshohocken, Pa.); a Test Method for Steady-StateHeat Flux Measurements and Thermal Transmission Properties by Means ofthe Guarded-Hot-Plate Apparatus (ASTM C177, ASTM International, WestConshohocken, Pa.); a Test Method for Steady-State Heat TransferProperties of Pipe Insulation (ASTM C335, ASTM International, WestConshohocken, Pa.); a Thin Heater Thermal Conductivity Test (ASTM C1114,ASTM International, West Conshohocken, Pa.); Determination of thermalresistance by means of guarded hot plate and heat flow meter methods (EN12667, British Standards Institution, United Kingdom); or Determinationof steady-state thermal resistance and related properties—Guarded hotplate apparatus (ISO 8203, International Organization forStandardization, Switzerland). Within the context of the presentdisclosure, thermal conductivity measurements are acquired according toASTM C177 standards, at a temperature of about 37.5° C. at atmosphericpressure, and a compression of about 2 psi, unless otherwise stated.Preferably, aerogel materials or compositions of the present disclosurehave a thermal conductivity of about 50 mW/mK or less, about 40 mW/mK orless, about 30 mW/mK or less, about 25 mW/mK or less, about 20 mW/mK orless, about 18 mW/mK or less, about 16 mW/mK or less, about 14 mW/mK orless, about 12 mW/mK or less, about 10 mW/mK or less, about 5 mW/mK orless, or in a range between any two of these values.

Within the context of the present disclosure, the term “density” refersto a measurement of the mass per unit volume of an aerogel material orcomposition. The term “density” generally refers to the true density ofan aerogel material, as well as the bulk density of an aerogelcomposition. Density is typically recorded as kg/m³ or g/cc. The densityof an aerogel material or composition may be determined by methods knownin the art, including, but not limited to: Standard Test Method forDimensions and Density of Preformed Block and Board-Type ThermalInsulation (ASTM C303, ASTM International, West Conshohocken, Pa.);Standard Test Methods for Thickness and Density of Blanket or BattThermal Insulations (ASTM C167, ASTM International, West Conshohocken,Pa.); or Determination of the apparent density of preformed pipeinsulation (ISO 18098, International Organization for Standardization,Switzerland). Within the context of the present disclosure, densitymeasurements are acquired according to ASTM C167 standards, unlessotherwise stated. Preferably, aerogel materials or compositions of thepresent disclosure have a density of about 0.60 g/cc or less, about 0.50g/cc or less, about 0.40 g/cc or less, about 0.30 g/cc or less, about0.25 g/cc or less, about 0.20 g/cc or less, about 0.18 g/cc or less,about 0.16 g/cc or less, about 0.14 g/cc or less, about 0.12 g/cc orless, about 0.10 g/cc or less, about 0.05 g/cc or less, about 0.01 g/ccor less, or in a range between any two of these values.

Within the context of the present disclosure, the term “hydrophobicity”refers to a measurement of the ability of an aerogel material orcomposition to repel water.

Hydrophobicity of an aerogel material or composition can be expressed interms of the liquid water uptake. Within the context of the presentdisclosure, the term “liquid water uptake” refers to a measurement ofthe potential of an aerogel material or composition to absorb orotherwise retain liquid water. Liquid water uptake can be expressed as apercent (by weight or by volume) of water which is absorbed or otherwiseretained by an aerogel material or composition when exposed to liquidwater under certain measurement conditions. The liquid water uptake ofan aerogel material or composition may be determined by methods known inthe art, including, but not limited to: Standard Test Method forDetermining the Water Retention (Repellency) Characteristics of FibrousGlass Insulation (ASTM C1511, ASTM International, West Conshohocken,Pa.); Standard Test Method for Water Absorption by Immersion of ThermalInsulation Materials (ASTM C1763, ASTM International, West Conshohocken,Pa.); Thermal insulating products for building applications:Determination of short term water absorption by partial immersion (EN1609, British Standards Institution, United Kingdom). Within the contextof the present disclosure, measurements of liquid water uptake areacquired according to ASTM C1511 standards, under ambient pressure andtemperature, unless otherwise stated. Preferably, aerogel materials orcompositions of the present disclosure can have a liquid water uptake ofaccording to ASTM C1511 of about 100 wt % or less, about 80 wt % orless, about 60 wt % or less, about 50 wt % or less, about 40 wt % orless, about 30 wt % or less, about 20 wt % or less, about 15 wt % orless, about 10 wt % or less, about 8 wt % or less, about 3 wt % or less,about 2 wt % or less, about 1 wt % or less, about 0.1 wt % or less, orin a range between any two of these values. Aerogel materials orcompositions of the present disclosure can have a liquid water uptake ofaccording to ASTM C1763 of about 100 vol wt % or less, about 80 wt % orless, about 60 wt % or less, about 50 wt % or less, about 40 wt % orless, about 30 wt % or less, about 20 wt % or less, about 15 wt % orless, about 10 wt % or less, about 8 wt % or less, about 3 wt % or less,about 2 wt % or less, about 1 wt % or less, about 0.1 wt % or less, orin a range between any two of these values. An aerogel material orcomposition which has improved liquid water uptake relative to anotheraerogel material or composition will have a lower percentage of liquidwater uptake/retention relative to the reference aerogel materials orcompositions.

Hydrophobicity of an aerogel material or composition can be expressed interms of the water vapor uptake. Within the context of the presentdisclosure, the term “water vapor uptake” refers to a measurement of thepotential of an aerogel material or composition to absorb water vapor.Water vapor uptake can be expressed as a percent (by weight) of waterwhich is absorbed or otherwise retained by an aerogel material orcomposition when exposed to water vapor under certain measurementconditions. The water vapor uptake of an aerogel material or compositionmay be determined by methods known in the art, including, but notlimited to: Standard Test Method for Determining the Water VaporSorption of Unfaced Mineral Fiber Insulation (ASTM C1104, ASTMInternational, West Conshohocken, Pa.). Within the context of thepresent disclosure, measurements of water vapor uptake are acquiredaccording to ASTM C1104 standards, under ambient pressure andtemperature, unless otherwise stated. Preferably, aerogel materials orcompositions of the present disclosure can have a water vapor uptake ofabout 50 wt % or less, about 40 wt % or less, about 30 wt % or less,about 20 wt % or less, about 15 wt % or less, about 10 wt % or less,about 8 wt % or less, about 3 wt % or less, about 2 wt % or less, about1 wt % or less, about 0.1 wt % or less, or in a range between any two ofthese values. An aerogel material or composition which has improvedwater vapor uptake relative to another aerogel material or compositionwill have a lower percentage of water vapor uptake/retention relative tothe reference aerogel materials or compositions.

Hydrophobicity of an aerogel material or composition can be expressed bymeasuring the equilibrium contact angle of a water droplet at theinterface with the surface of the material. Aerogel materials orcompositions of the present disclosure can have a water contact angle ofabout 90° or more, about 120° or more, about 130° or more, about 140° ormore, about 150° or more, about 160° or more, about 170° or more, about175° or more, or in a range between any two of these values.

Aerogels are described as a framework of interconnected structures whichare most commonly comprised of interconnected oligomers, polymers orcolloidal particles. An aerogel framework can be made from a range ofprecursor materials, including: inorganic precursor materials (such asprecursors used in producing silica-based aerogels); organic precursormaterials (such precursors used in producing carbon-based aerogels);hybrid inorganic/organic precursor materials; and combinations thereof.Within the context of the present invention, the term “amalgam aerogel”refers to an aerogel produced from a combination of two or moredifferent gel precursors.

Inorganic aerogels are generally formed from metal oxide or metalalkoxide materials. The metal oxide or metal alkoxide materials can bebased on oxides or alkoxides of any metal that can form oxides. Suchmetals include, but are not limited to: silicon, aluminum, titanium,zirconium, hafnium, yttrium, vanadium, cerium, and the like. Inorganicsilica aerogels are traditionally made via the hydrolysis andcondensation of silica-based alkoxides (such as tetraethoxylsilane), orvia gelation of silicic acid or water glass. Other relevant inorganicprecursor materials for silica based aerogel synthesis include, but arenot limited to: metal silicates such as sodium silicate or potassiumsilicate, alkoxysilanes, partially hydrolyzed alkoxysilanes,tetraethoxylsilane (TEOS), partially hydrolyzed TEOS, condensed polymersof TEOS, tetramethoxylsilane (TMOS), partially hydrolyzed TMOS,condensed polymers of TMOS, tetra-n-propoxysilane, partially hydrolyzedand/or condensed polymers of tetra-n-propoxysilane, polyethylsilicates,partially hydrolyzed polyethysilicates, monomeric alkylalkoxy silanes,bis-trialkoxy alkyl or aryl silanes, polyhedral silsesquioxanes, orcombinations thereof.

In one embodiment of the present invention, pre-hydrolyzed TEOS, such asSilbond H-5 (SBH5, Silbond Corp), which is hydrolyzed with awater/silica ratio of about 1.9-2, may be used as commercially availableor may be further hydrolyzed prior to incorporation into the gellingprocess. Partially hydrolyzed TEOS or TMOS, such as polyethysilicate(Silbond 40) or polymethylsilicate may also be used as commerciallyavailable or may be further hydrolyzed prior to incorporation into thegelling process.

Inorganic aerogels can also include gel precursors which comprise atleast one hydrophobic group, such as alkyl metal alkoxides, cycloalkylmetal alkoxides, and aryl metal alkoxides, which can impart or improvecertain properties in the gel such as stability and hydrophobicity.Inorganic silica aerogels can specifically include hydrophobicprecursors such as alkylsilanes or arylsilanes. Hydrophobic gelprecursors can be used as primary precursor materials to form theframework of a gel material. However, hydrophobic gel precursors aremore commonly used as co-precursors in combination with simple metalalkoxides in the formation of amalgam aerogels. Hydrophobic inorganicprecursor materials for silica based aerogel synthesis include, but arenot limited to: trimethyl methoxysilane [TMS], dimethyl dimethoxysilane[DMS], methyl trimethoxysilane [MTMS], trimethyl ethoxysilane, dimethyldiethoxysilane [DMDS], methyl triethoxysilane [MTES], ethyltriethoxysilane [ETES], diethyl diethoxysilane, ethyl triethoxysilane,propyl trimethoxysilane, propyl triethoxysilane, phenyltrimethoxysilane, phenyl tri ethoxysilane [PhTES], hexamethyldisilazaneand hexaethyldisilazane, and the like.

Aerogels may also be treated to impart or improve hydrophobicity.Hydrophobic treatment can be applied to a sol-gel solution, a wet-gelprior to liquid phase extraction, or to an aerogel subsequent to liquidphase extraction. Hydrophobic treatment is especially common in theproduction of metal oxide aerogels, such as silica aerogels. An exampleof a hydrophobic treatment of a gel is discussed below in greaterdetail, specifically in the context of treating a silica wet-gel.However, the specific examples and illustrations provided herein are notintended to limit the scope of the present invention to any specifictype of hydrophobic treatment procedure or aerogel substrate. Thepresent invention can include any gel or aerogel known to those in theart, as well as associated methods of hydrophobic treatment of theaerogels, in either wet-gel form or dried aerogel form.

Hydrophobic treatment is carried out by reacting a hydroxy moiety on agel, such as a silanol group (Si—OH) present on a framework of a silicagel, with a functional group of a hydrophobizing agent. The resultingreaction converts the silanol group and the hydrophobizing agent into ahydrophobic group on the framework of the silica gel. The hydrophobizingagent compound can react with hydroxyl groups on the gel according thefollowing reaction: R_(N)MX_(4-N) (hydrophobizing agent)+MOH(silanol)→MOMR_(N) (hydrophobic group)+HX. Hydrophobic treatment cantake place both on the outer macro-surface of a silica gel, as well ason the inner-pore surfaces within the porous network of a gel.

A gel can be immersed in a mixture of a hydrophobizing agent and anoptional hydrophobic-treatment solvent in which the hydrophobizing agentis soluble, and which is also miscible with the gel solvent in thewet-gel. A wide range of hydrophobic-treatment solvents can be used,including solvents such as methanol, ethanol, isopropanol, xylene,toluene, benzene, dimethylformamide, and hexane. Hydrophobizing agentsin liquid or gaseous form may also be directly contacted with the gel toimpart hydrophobicity.

The hydrophobic treatment process can include mixing or agitation tohelp the hydrophobizing agent to permeate the wet-gel. The hydrophobictreatment process can also include varying other conditions such astemperature and pH to further enhance and optimize the treatmentreactions. After the reaction is completed, the wet-gel is washed toremove unreacted compounds and reaction by-products.

Hydrophobizing agents for hydrophobic treatment of an aerogel aregenerally compounds of the formula: R_(N)MX_(4-N); where M is the metal;R is a hydrophobic group such as CH₃, CH₂CH₃, C₆H₆, or similarhydrophobic alkyl, cycloalkyl, or aryl moieties; and X is a halogen,usually Cl. Specific examples of hydrophobizing agents include, but arenot limited to: trimethylchlorosilane [TMCS], triethylchlorosilane[TECS], triphenylchlorosilane [TPCS], dimethylchlorosilane [DMCS],dimethyldichlorosilane [DMDCS], and the like. Hydrophobizing agents canalso be of the formula: Y(R₃M)₂; where M is a metal; Y is bridging groupsuch as NH or O; and R is a hydrophobic group such as CH₃, CH₂CH₃, C₆H₆,or similar hydrophobic alkyl, cycloalkyl, or aryl moieties. Specificexamples of such hydrophobizing agents include, but are not limited to:hexamethyldisilazane [HMDZ] and hexamethyldisiloxane [HMDSO].Hydrophobizing agents can further include compounds of the formula:R_(N)MV_(4-N), wherein V is a reactive or leaving group other than ahalogen. Specific examples of such hydrophobizing agents include, butare not limited to: vinyltriethoxysilane and vinyltrimethoxysilane.

Organic aerogels are generally formed from carbon-based polymericprecursors. Such polymeric materials include, but are not limited to:resorcinol formaldehydes (RF), polyimide, polyacrylate, polymethylmethacrylate, acrylate oligomers, polyoxyalkylene, polyurethane,polyphenol, polybutadiane, trialkoxysilyl-terminatedpolydimethylsiloxane, polystyrene, polyacrylonitrile, polyfurfural,melamine-formaldehyde, cresol formaldehyde, phenol-furfural, polyether,polyol, polyisocyanate, polyhydroxybenzene, polyvinyl alcoholdialdehyde, polycyanurates, polyacrylamides, various epoxies, agar,agarose, chitosan, and combinations thereof. As one example, organic RFaerogels are typically made from the sol-gel polymerization ofresorcinol or melamine with formaldehyde under alkaline conditions.

Organic/inorganic hybrid aerogels are mainly comprised of ormosil(organically modified silica) aerogels. These ormosil materials includeorganic components which are covalently bonded to a silica network.Ormosils are typically formed through the hydrolysis and condensation oforganically modified silanes, R—Si(OX)₃, with traditional alkoxideprecursors, Y(OX)₄. In these formulas: X may represent, for example,CH₃, C₂H₅, C₃H₇, C₄H₉; Y may represent, for example, Si, Ti, Zr, or Al;and R may be any organic fragment such as methyl, ethyl, propyl, butyl,isopropyl, methacrylate, acrylate, vinyl, epoxide, and the like. Theorganic components in ormosil aerogel may also be dispersed throughoutor chemically bonded to the silica network.

Within the context of the present invention, the term “ormosil”encompasses the foregoing materials as well as other organicallymodified ceramics, sometimes referred to as “ormocers.” Ormosils areoften used as coatings where an ormosil film is cast over a substratematerial through, for example, the sol-gel process. Examples of otherorganic-inorganic hybrid aerogels of the invention include, but are notlimited to, silica-polyether, silica-PMMA, silica-chitosan, carbides,nitrides, and other combinations of the aforementioned organic andinorganic aerogel forming compounds. Published US Pat. App. 20050192367(Paragraphs [0022]-[0038] and [0044]-[0058]) includes teachings of suchhybrid organic-inorganic materials, and is hereby incorporated byreference according to the individually cited sections and paragraphs.

Aerogels of the present invention are preferably inorganic silicaaerogels formed primarily from alcohol solutions of hydrolyzed silicateesters formed from silicon alkoxides. However, the invention as a wholemay be practiced with any other aerogel compositions known to those inthe art, and is not limited to any one precursor material or amalgammixture of precursor materials.

Production of an aerogel generally includes the following steps: i)formation of a sol-gel solution; ii) formation of a gel from the sol-gelsolution; and iii) extracting the solvent from the gel materials throughinnovative processing and extraction, to obtain a dried aerogelmaterial. This process is discussed below in greater detail,specifically in the context of forming inorganic aerogels such as silicaaerogels. However, the specific examples and illustrations providedherein are not intended to limit the present invention to any specifictype of aerogel and/or method of preparation. The present invention caninclude any aerogel formed by any associated method of preparation knownto those in the art.

The first step in forming an inorganic aerogel is generally theformation of a sol-gel solution through hydrolysis and condensation ofmetal alkoxide precursors in an alcohol-based solvent. Major variablesin the formation of inorganic aerogels include the type of alkoxideprecursors included in the sol-gel solution, the nature of the solvent,the processing temperature and pH of the sol-gel solution (which may bealtered by addition of an acid or a base), and precursor/solvent/waterratio within the sol-gel solution. Control of these variables in forminga sol-gel solution can permit control of the growth and aggregation ofthe gel framework during the subsequent transition of the gel materialfrom the “sol” state to the “gel” state. While properties of theresulting aerogels are affected by the pH of the precursor solution andthe molar ratio of the reactants, any pH and any molar ratios thatpermit the formation of gels may be used in the present disclosure.

A sol-gel solution is formed by combining at least one gelling precursorwith a solvent. Suitable solvents for use in forming a sol-gel solutioninclude lower alcohols with 1 to 6 carbon atoms, preferably 2 to 4,although other solvents can be used as known to those with skill in theart. Examples of useful solvents include, but are not limited to:methanol, ethanol, isopropanol, ethyl acetate, ethyl acetoacetate,acetone, dichloromethane, tetrahydrofuran, and the like. Multiplesolvents can also be combined to achieve a desired level of dispersionor to optimize properties of the gel material. Selection of optimalsolvents for the sol-gel and gel formation steps thus depends on thespecific precursors, fillers and additives being incorporated into thesol-gel solution; as well as the target processing conditions forgelling and liquid phase extraction, and the desired properties of thefinal aerogel materials.

Water can also be present in the precursor-solvent solution. The wateracts to hydrolyze the metal alkoxide precursors into metal hydroxideprecursors. The hydrolysis reaction can be (using TEOS in ethanolsolvent as an example): Si(OC₂H₅)₄+4H₂O→Si(OH)₄+4(C₂H₅OH). The resultinghydrolyzed metal hydroxide precursors remain suspended in the solventsolution in a “sol” state, either as individual molecules or as smallpolymerized (or oligomarized) colloidal clusters of molecules. Forexample, polymerization/condensation of the Si(OH)₄ precursors can occuras follows: 2 Si(OH)₄═(OH)₃Si—O—Si(OH)₃+H₂O. This polymerization cancontinue until colloidal clusters of polymerized (or oligomarized) SiO₂(silica) molecules are formed.

Acids and bases can be incorporated into the sol-gel solution to controlthe pH of the solution, and to catalyze the hydrolysis and condensationreactions of the precursor materials. While any acid may be used tocatalyze precursor reactions and to obtain a lower pH solution,preferable acids include: HCl, H₂SO₄, H₃PO₄, oxalic acid and aceticacid. Any base may likewise be used to catalyze precursor reactions andto obtain a higher pH solution, with a preferable base comprising NH₄OH.

The sol-gel solution can include additional co-gelling precursors, aswell as filler materials and other additives. Filler materials and otheradditives may be dispensed in the sol-gel solution at any point beforeor during the formation of a gel. Filler materials and other additivesmay also be incorporated into the gel material after gelation throughvarious techniques known to those in the art. Preferably, the sol-gelsolution comprising the gelling precursors, solvents, catalysts, water,filler materials and other additives is a homogenous solution which iscapable of effective gel formation under suitable conditions.

Once a sol-gel solution has been formed and optimized, the gel-formingcomponents in the sol-gel can be transitioned into a gel material. Theprocess of transitioning gel-forming components into a gel materialcomprises an initial gel formation step wherein the gel solidifies up tothe gel point of the gel material. The gel point of a gel material maybe viewed as the point where the gelling solution exhibits resistance toflow and/or forms a substantially continuous polymeric frameworkthroughout its volume. A range of gel-forming techniques are known tothose in the art. Examples include, but are not limited to: maintainingthe mixture in a quiescent state for a sufficient period of time;adjusting the pH of the solution; adjusting the temperature of thesolution; directing a form of energy onto the mixture (ultraviolet,visible, infrared, microwave, ultrasound, particle radiation,electromagnetic); or a combination thereof.

The process of transitioning gel-forming components into a gel materialcan also include an aging step (also referred to as curing) prior toliquid phase extraction. Aging a gel material after it reaches its gelpoint can further strengthen the gel framework by increasing the numberof cross-linkages within the network. The duration of gel aging can beadjusted to control various properties within the resulting aerogelmaterial. This aging procedure can be useful in preventing potentialvolume loss and shrinkage during liquid phase extraction. Aging caninvolve: maintaining the gel (prior to extraction) at a quiescent statefor an extended period; maintaining the gel at elevated temperatures;adding cross-linkage promoting compounds; or any combination thereof.The preferred temperatures for aging are usually between about 10° C.and about 100° C. The aging of a gel material typically continues up tothe liquid phase extraction of the wet-gel material.

The time period for transitioning gel-forming materials into a gelmaterial includes both the duration of the initial gel formation (frominitiation of gelation up to the gel point), as well as the duration ofany subsequent curing and aging of the gel material prior to liquidphase extraction (from the gel point up to the initiation of liquidphase extraction). The total time period for transitioning gel-formingmaterials into a gel material is typically between about 1 minute andseveral days, preferably about 30 hours or less, about 24 hours or less,about 15 hours or less, about 10 hours or less, about 6 hours or less,about 4 hours or less, about 2 hours or less, about 1 hour or less,about 30 minutes or less, or about 15 minutes or less.

The resulting gel material may be washed in a suitable secondary solventto replace the primary reaction solvent present in the wet-gel. Suchsecondary solvents may be linear monohydric alcohols with 1 or morealiphatic carbon atoms, dihydric alcohols with 2 or more carbon atoms,branched alcohols, cyclic alcohols, alicyclic alcohols, aromaticalcohols, polyhydric alcohols, ethers, ketones, cyclic ethers or theirderivative.

Once a gel material has been formed and processed, the liquid phase ofthe gel can then be at least partially extracted from the wet-gel usingextraction methods, including innovative processing and extractiontechniques, to form an aerogel material. Liquid phase extraction, amongother factors, plays an important role in engineering thecharacteristics of aerogels, such as porosity and density, as well asrelated properties such as thermal conductivity. Generally, aerogels areobtained when a liquid phase is extracted from a gel in a manner thatcauses low shrinkage to the porous network and framework of the wet gel.

Aerogels are commonly formed by removing the liquid mobile phase fromthe gel material at a temperature and pressure near or above thecritical point of the liquid mobile phase. Once the critical point isreached (near critical) or surpassed (supercritical) (i.e pressure andtemperature of the system is at or higher than the critical pressure andcritical temperature respectively) a new supercritical phase appears inthe fluid that is distinct from the liquid or vapor phase. The solventcan then be removed without introducing a liquid-vapor interface,capillary pressure, or any associated mass transfer limitationstypically associated with liquid-vapor boundaries. Additionally, thesupercritical phase is more miscible with organic solvents in general,thus having the capacity for better extraction. Co-solvents and solventexchanges are also commonly used to optimize the supercritical fluiddrying process.

If evaporation or extraction occurs below the supercritical point,strong capillary forces generated by liquid evaporation can causeshrinkage and pore collapse within the gel material. Maintaining themobile phase near or above the critical pressure and temperature duringthe solvent extraction process reduces the negative effects of suchcapillary forces. In some embodiments of the present invention, the useof near-critical conditions just below the critical point of the solventsystem may allow production of aerogel materials or compositions withsufficiently low shrinkage, thus producing a commercially viableend-product.

Several additional aerogel extraction techniques are known in the art,including a range of different approaches in the use of supercriticalfluids in drying aerogels. For example, Kistler (J. Phys. Chem. (1932)36: 52-64) describes a simple supercritical extraction process where thegel solvent is maintained above its critical pressure and temperature,thereby reducing evaporative capillary forces and maintaining thestructural integrity of the gel network. U.S. Pat. No. 4,610,863describes an extraction process where the gel solvent is exchanged withliquid carbon dioxide and subsequently extracted at conditions wherecarbon dioxide is in a supercritical state. U.S. Pat. No. 6,670,402teaches extracting a liquid phase from a gel via rapid solvent exchangeby injecting supercritical (rather than liquid) carbon dioxide into anextractor that has been pre-heated and pre-pressurized to substantiallysupercritical conditions or above, thereby producing aerogels. U.S. Pat.No. 5,962,539 describes a process for obtaining an aerogel from apolymeric material that is in the form a sol-gel in an organic solvent,by exchanging the organic solvent for a fluid having a criticaltemperature below a temperature of polymer decomposition, andsupercritically extracting the fluid/sol-gel. U.S. Pat. No. 6,315,971discloses a process for producing gel compositions comprising: drying awet gel comprising gel solids and a drying agent to remove the dryingagent under drying conditions sufficient to reduce shrinkage of the gelduring drying. U.S. Pat. No. 5,420,168 describes a process wherebyResorcinol/Formaldehyde aerogels can be manufactured using a simple airdrying procedure. U.S. Pat. No. 5,565,142 describes drying techniques inwhich the gel surface is modified to be stronger and more hydrophobic,such that the gel framework and pores can resist collapse during ambientdrying or subcritical extraction. Other examples of extracting a liquidphase from aerogel materials can be found in U.S. Pat. Nos. 5,275,796and 5,395,805.

One preferred embodiment of extracting a liquid phase from the wet-geluses supercritical conditions of carbon dioxide, including, for example:first substantially exchanging the primary solvent present in the porenetwork of the gel with liquid carbon dioxide; and then heating the wetgel (typically in an autoclave) beyond the critical temperature ofcarbon dioxide (about 31.06° C.) and increasing the pressure of thesystem to a pressure greater than the critical pressure of carbondioxide (about 1070 psig). The pressure around the gel material can beslightly fluctuated to facilitate removal of the supercritical carbondioxide fluid from the gel. Carbon dioxide can be recirculated throughthe extraction system to facilitate the continual removal of the primarysolvent from the wet gel. Finally, the temperature and pressure areslowly returned to ambient conditions to produce a dry aerogel material.Carbon dioxide can also be pre-processed into a supercritical stateprior to being injected into an extraction chamber.

One example of an alternative method of forming an aerogel includes theacidification of basic metal oxide precursors (such as sodium silicate)in water to make a hydrogel. Salt by-products may be removed from thesilicic acid precursor by ion-exchange and/or by washing subsequentlyformed gels with water. Removing the water from the pores of the gel canbe performed via exchange with a polar organic solvent such as ethanol,methanol, or acetone. The liquid phase in the gel is then at leastpartially extracted using innovative processing and extractiontechniques.

Another example of an alternative method of forming aerogels includesreducing the damaging capillary pressure forces at the solvent/poreinterface by chemical modification of the matrix materials in their wetgel state via conversion of surface hydroxyl groups to hydrophobictrimethylsilylethers, thereby allowing for liquid phase extraction fromthe gel materials at temperatures and pressures below the critical pointof the solvent.

Large-scale production of aerogel materials or compositions can becomplicated by difficulties related to the continuous formation of gelmaterials on a large scale; as well as the difficulties related toliquid phase extraction from gel materials in large volumes usinginnovative processing and extraction techniques. Aerogel materials orcompositions of the present disclosure are preferably accommodating toproduction on a large scale. In certain embodiments, gel materials ofthe present disclosure can be produced in large scale through acontinuous casting and gelation process. In certain embodiments, aerogelmaterials or compositions of the present disclosure are produced in alarge scale which requires the use of large scale extraction vessels.Large scale extraction vessels of the present disclosure can includeextraction vessels which have a volume of about 0.1 m³ or more, about0.25 m³ or more, about 0.5 m³ or more, or about 0.75 m³ or more.

Large-scale production of aerogel compositions can include a conveyorbased system that combines gel precursors with a continuousreinforcement sheet, such as a fiber reinforcement sheet or open-cellfoam reinforcement sheet, at one end of a conveyor to produce acontinuous reinforced gel sheet. This reinforced gel sheet may be woundin a plurality of layers (preferably around a mandrel with a uniformtension) and processed in subsequent chemical treatment, aging anddrying steps. Additional separator layers can be co-wound between thegel sheet layers to facilitate aging or drying of the gel material, suchas providing a flow path for aging agents or drying materials. Theseparator layer can be impermeable (preferably impermeable to fluids atpressures below 1 psi, 5 psi or 10 psi) or permeable. Permeable layersmay be in the form of perforated plastic sheets, mesh like material,perforated foil, or the like.

FIG. 1 illustrates one embodiment of a conveyor based system 100 forlarge-scale production of aerogel compositions. A gel precursor solution110 is mixed with a catalyst solution 120 in a mixing section 114. Theflow of the gel precursor solution 110 and catalyst solution 120 arecontrolled by flow controllers 130. A reinforcement material 150 isprovided onto a conveyor system 140. The reinforcement material 150 canbe a continuous sheet from a roll of reinforcement material. Thereinforcement material 150 can also comprise segments of reinforcementmaterial. In a preferred embodiment, the reinforcement material 150 is afiber reinforcement material or an open-cell foam reinforcementmaterial. The precursor solution (comprising gel precursor and catalyst)are dispensed onto conveyor belt 140 and combined with reinforcementmaterial 150. The gel forming precursors in the gel precursor solutionare transitioned into a gel material as the reinforcement material isadvanced by the conveyor system 140. The resulting reinforced gel sheetis wound for subsequent chemical treatment, aging and drying steps. Anadditional separator layer 164 can be co-wound between the gel sheetlayers 160.

Large-scale production of aerogel compositions can comprise asemi-continuous, batch-based process which is commonly referred as agel-in-a-roll process. FIG. 2 illustrates one embodiment of asemi-continuous, batch-based system 200 for large-scale production ofaerogel compositions. Sheets of reinforcement material are rolled intoplurality of layers as a preform roll 220 and placed into a container210. Additional separator layers 250 may be co-rolled with thereinforcement material in the preform roll 220. The separator layers maybe impermeable (preferably impermeable to fluids at pressures below 1psi, 5 psi or 10 psi) or permeable. Permeable layers may be in the formof perforated plastic sheets, or mesh like material, perforated foil, orthe like. A gel precursor solution 240 is infused or combined with thereinforcement material of the preform roll 220. The gel formingprecursors in the gel precursor solution are transitioned into a gelmaterial. The resulting reinforced gel sheet can be immediately advancedfor subsequent chemical treatment, aging and drying steps. The resultingreinforced gel sheet can also be unwound, and then rewound withdifferent separator layers prior to subsequent chemical treatment, agingand drying steps.

Aerogel composites can be laminated or faced with other materials, suchas reinforcing layers of facing materials. In one embodiment, thepresent invention comprises a multi-layer laminate comprising at leastone base layer comprising a reinforced aerogel composition, and at leastone facing layer. In one embodiment, the facing layer comprises areinforcing material. In one embodiment, the reinforced aerogelcomposition is reinforced with a fiber reinforcement layer or anopen-cell foam reinforcement layer. In one embodiment, the presentinvention comprises a multi-layer laminate comprising a base layercomprising a reinforced aerogel composition, and at least two facinglayers comprising reinforcing materials, wherein the two facing layersare an opposite surfaces of the base layer. The a multi-layer aerogellaminate composite can be produced according to the methods andmaterials described in US Patent Application 20070173157, paragraphs[0004], [0010], [0011], [0017]-[0021], and [0023]-[0027]; which methodsand materials are incorporated herein by reference according to thespecific paragraphs cited above.

The facing layer can comprise materials which will help provide specificcharacteristics to the final composite structure, such as improvedflexibility or reduced dusting. The facing materials can be stiff orflexible. The facing materials can comprise reflective foils. In oneembodiment, the facing layer comprises a polymeric sheet; morespecifically a polymeric sheet which comprises polyesters,polyethylenes, polyurethanes, polypropylenes, polyacrylonitriles,polyamids, aramids; and more specifically polymers such aspolyethyleneterphthalate, low density polyethylene, ethylene-propyleneco-polymers, poly(4-methyl-pentane), polytetrafluoroethylene,poly(1-butene), polystyrene, polyvinylacetatae, polyvinylchloride,polyvinylidenechloride, polyvinylfluoride, polyvinylacrylonitrile,plymethylmethacrylate, polyoxymethylene, polyphenylenesulfone,cellulosetriacetate, polycarbonate, polyethylene naphthalate,polycaprolactam, polyhexamethyleneadipamide, polyundecanoamide,polyimide, or combinations thereof. In one embodiment, the polymericsheet comprises or consists essentially of an expanded polymericmaterial; more specifically an expanded polymeric material comprisingPTFE (ePTFE), expanded polypropylene (ePP), expanded polyethylene (ePE),expanded polystyrene (ePS), or combinations thereof. In one preferredembodiment, the facing material consists essentially of an expandedpolymeric material. In one embodiment, the polymeric sheet comprises orconsists essentially of a microporous polymeric material characterizedby a pore size ranging from 0.1 μm to 210 μm, 0.1 μm to 115 μm, 0.1 μmto 15 μm, or 0.1 μm to 0.6 μm.

In one embodiment, the facing layer material comprises or consistsessentially of a fluoropolymeric material. Within the context of thepresent disclosure, the terms “fluoropolymeric” or “fluoropolymermaterial” refer to materials comprised primarily of polymericfluorocarbons. Suitable fluoropolymeric facing layer materials include,but are not limited to: polytetrafluoroethylene (PTFE), includingmicroporous PTFE described in U.S. Pat. No. 5,814,405, and expanded PTFE(ePTFE) such as Gore-Tex® (available from W.L. Gore); polyvinylfluoride(PVF); polyvinylidene fluoride (PVDF); perfluoroalkoxy (PFA);fluorinated ethylene-propylene (FEP); Polychlorotrifluoroethylene(PCTFE); Ethylene tetrafluoroethylene (ETFE); polyvinylidene fluoride(PVDF); ethylene chlorotrifluoroethylene (ECTFE); and combinationsthereof. In one preferred embodiment, the facing material consistsessentially of a fluoropolymeric material. In one preferred embodiment,the facing material consists essentially of an expanded PTFE (ePTFE)material.

In one embodiment, the facing layer material comprises or consistsessentially of a non-fluoropolymeric material. Within the context of thepresent disclosure, the terms “non-fluoropolymeric” or“non-fluoropolymer material” refer to materials which do not comprise afluoropolymeric material. Suitable non-fluoropolymeric facing layermaterials include, but are not limited to: aluminized Mylar; low densitypolyethylene, such as Tyvek® (available from DuPont); rubber or rubbercomposites; elastic fibers such as spandex, nylon, lycra or elastane;and combinations thereor. In one embodiment, the facing material is aflexible facing material.

The facing layer can be attached to the base layer by using adhesiveswhich are suitable for securing inorganic or organic facing materials tothe reinforcing material of the base layer. Examples of adhesives whichcan be used in the present invention include, but are not limited to:cement based adhesives, sodium silicates, latexes, pressure sensitiveadhesives, silicone, polystyrene, aerosol adhesives, urethane, acrylateadhesives, hot melt boding systems, boding systems commerciallyavailable from 3M, epoxy, rubber resin adhesives, polyurethane adhesivemixtures such as those described in U.S. Pat. No. 4,532,316.

The facing layer can also be attached to the base layer by usingnon-adhesive materials or techniques which are suitable for securinginorganic or organic facing materials to the reinforcing material of thebase layer. Examples of non-adhesive materials or techniques which canbe used in the present invention include, but are not limited to: heatsealing, ultrasonic stitching, RF sealing, stitches or threading,sealing bags, rivets or buttons, clamps, wraps, or other non-adhesivelamination materials.

The facing layer can be attached to the base layer at any stage ofproduction of the aerogel composite material. In one embodiment, thefacing layer is attached to the base layer after infusion of the sol gelsolution into the base reinforcement material but prior to gelation. Inanother embodiment, the facing layer is attached to the base layer afterinfusion of the sol gel solution into the base reinforcement materialand after subsequent gelation, but prior to aging or drying the gelmaterial. In yet another embodiment, the facing layer is attached to thebase layer after aging and drying the gel material. In a preferredembodiment, the facing layer is attached to the reinforcement materialof the base layer prior to infusion of the sol gel solution into thebase reinforcement material.

The facing layer can be solid and fluid impermeable. The facing layercan be porous and fluid permeable. In a preferred embodiment, the facinglayer is porous and fluid permeable, and contains pores or holes withdiameters large enough to allow fluids to diffuse through the facingmaterial. In another preferred embodiment, the facing layer is attachedto the reinforcement material of the base layer prior to infusion of thesol gel solution into the base reinforcement material, wherein thefacing layer is porous and fluid permeable, and contains pores or holeswith diameters large enough to allow fluids to diffuse through thefacing material. In yet another preferred embodiment, the facing layeris attached to an open-cell foam reinforcement material prior toinfusion of the sol gel solution into the foam reinforcement material,wherein the facing layer is porous and fluid permeable, and containspores or holes with diameters large enough to allow fluids to diffusethrough the facing material.

Production of multi-layer gel or aerogel compositions can include thefollowing steps: a) attaching a fluid-permeable facing layer to a sheetof reinforcement material to produce a laminated reinforcement sheet,wherein the facing layer contains pores or holes with diameters largeenough to allow fluids to diffuse through the facing material; b)infusing a gel precursor solution through the facing layer into thereinforcement sheet; and c) transitioning the gel precursor materialinto a gel material comprising a gel framework. A portion of the gelprecursor solution is likely to be retained within the pores or holes ofthe facing layer, such that the gel framework in the reinforcementmaterial of the base layer will extend into at least a portion of thefacing layer. The resulting product is a multi-layer gel compositioncomprising: a) at least one base layer comprising a reinforcementmaterial, and an gel framework integrated within the reinforcementmaterial; and b) at least one facing layer comprising a fluid-permeablefacing material, and an gel framework integrated within thefluid-permeable facing material; wherein at least a portion of the gelframework of the base layer extends into and is continuous with at leasta portion of the gel framework of the facing layer.

Large-scale production of multi-layer aerogel compositions can include aconveyor based system, wherein the production comprises the followingsteps: a) attaching at least one fluid-permeable facing layer to a sheetof reinforcement material to produce a laminated reinforcement sheet,wherein the facing layer contains pores or holes with diameters largeenough to allow fluids to diffuse through; and b) combining a gelprecursor solution with the laminated reinforcement sheet at one end ofa conveyor to produce a continuous reinforced gel sheet laminate;wherein at least a portion of the gel precursor solution infuses throughthe facing layer into the reinforcement sheet; and wherein the gelprecursor solution is combined with the laminated reinforcement sheet ata rate which allows the gel precursor solution to pass through thefacing layer and infiltrate the reinforcement sheet. In a preferredembodiment, the reinforcement material comprises an open-cell foamreinforcement material.

The reinforced, laminated gel sheet may be wound into a plurality oflayers (preferably around a mandrel with a uniform tension) andprocessed in subsequent chemical treatment, aging and drying steps. Anadditional separator layers can be co-wound between the gel sheet layersto facilitate aging or drying of the gel material, such as providing aflow path for aging agents or drying materials. In a preferredembodiment, the facing layer provides a flow path for aging agents ordrying materials, such that an additional separator layer is notrequired for aging and drying of the gel material.

Large-scale production of multi-layer aerogel compositions can include asemi-continuous, batch-based process which is commonly referred as agel-in-a-roll process, wherein the production comprises the followingsteps: a) attaching a fluid-permeable facing layer to a sheet ofreinforcement material, wherein the facing layer contains pores or holeswith diameters large enough to allow fluids to diffuse through; b)rolling the laminated reinforcement materials into plurality of layersas a preform roll; and c) combining a gel precursor solution with thepreform role. Additional separator layers may be co-rolled with thereinforcement material in the preform roll to provide a flow path forthe gel precursor solution, aging agents, and drying materials. In apreferred embodiment, the facing layer provides a flow path for the gelprecursor solution, aging agents, and drying materials, such that anadditional separator layer is not required. In a preferred embodiment,the reinforcement material comprises an open-cell foam reinforcementmaterial.

Reinforced aerogel composites of the present invention may be shapedinto a range of three dimensional forms, including paneling, pipepreforms, half-shell preforms, elbows, joints, and other shapesregularly required in the application of insulation materials toindustrial and commercial applications. In one embodiment, thereinforcement material is formed into a desired shape prior to beinginfused with gel precursor material. The gel material is processed in amanner which allows the preform to maintain its shape, thus resulting ina reinforced aerogel preform of a desired shape. This technique offorming shaped aerogel preforms can be challenging and inefficientbecause of the difficulties required to process gel materials of variousshapes and configurations.

In one embodiment, the reinforced gel composite is initially in a sheetform, and is processed into a desired three dimensional shape aftergelation of the gel material, or after gelation of the gel material andsubsequent drying. In a preferred embodiment, a sheet of reinforcedaerogel material is heated to a desired temperature, formed into adesired shape, and then allowed to cool. This technique of shaping areinforced aerogel material is particularly effective with foamreinforcement materials. In a preferred embodiment, a sheet ofreinforced aerogel material comprising a foam reinforcement material isheated to a desired temperature, formed into a desired shape, and thenallowed to cool. The desired temperature for heating the aerogelmaterial should be a temperature above the softening point of the foamreinforcement material, and below the maximum use temperature of thereinforcement material and below the self-heating temperature of theaerogel material. The desired temperature should be high enough that thereinforcement material is soft and flexible enough to be formed into adesire shape, but still stable enough to support the aerogel materialduring the shaping process. The desired temperature for heating theaerogel material will thus vary depending on the type of reinforcementmaterial and aerogel material being used. In one embodiment, the desiredtemperature is between 50° C. and 200° C., between 75° C. and 200° C.,between 100° C. and 175° C., between 120° C. and 160° C., or about 150°C.

In one embodiment, the reinforced gel composite is initially in a blockor molded form, and is processed into a desired three dimensional shapeafter gelation of the gel material, or after gelation of the gelmaterial and subsequent drying. In one embodiment, a block of reinforcedaerogel material is formed by combining the reinforcement material andthe gel precursor in a mold of a certain shape. The material in the moldis allowed to gel, and then dried to produce a shaped aerogel composite.In a preferred embodiment, a block of reinforced aerogel material isproduced, and then cut or lathed into a desired shape. In anotherpreferred embodiment, a block of reinforced aerogel material isproduced, and then cut into individual sheet using a skiving machine orapparatus.

Aerogel composition can also include an opacifier to reduce theradiative component of heat transfer. At any point prior to gelformation, opacifying compounds or precursors thereof may be dispersedinto the mixture comprising gel precursors. Examples of opacifyingcompounds include, but are not limited to: Boron Carbide [13₄C],Diatomite, Manganese ferrite, MnO, NiO, SnO, Ag₂O, Bi₂O₃, carbon black,titanium oxide, iron titanium oxide, zirconium silicate, zirconiumoxide, iron (I) oxide, iron (III) oxide, manganese dioxide, irontitanium oxide (ilmenite), chromium oxide, carbides (such as SiC, TiC orWC), or mixtures thereof. Examples of opacifying compound precursorsinclude, but are not limited to: TiOSO₄ or TiOCl₂.

The embodiments of the present invention can be practiced using any ofthe processing, extraction and treatment techniques discussed herein, aswell as other processing, extraction and treatment techniques known tothose in the art for producing aerogels, aerogel-like materials, andaerogel compositions as defined herein.

The aerogel materials and compositions of the present invention havebeen shown to be highly effective as insulation materials. However,application of the methods and materials of the present invention arenot intended to be limited to applications related to insulation. Themethods and materials of the present invention can be applied to anysystem or application which would benefit from the unique combination ofproperties or procedures provided by the materials and methods of thepresent invention. The applications include, but are not limited to,thermal barriers and panels (including fire barriers and panels),insulation (including in apparel, buildings, piping, or industrialequipment), acoustical barriers, electronics, shock impact isolators,and chemical catalysis. Applications utilizing the composites of theinvention may use single or multiple layers of the composites, and maymechanically alter composites of the invention such as through cuttingthem to size.

The following examples provide various non-limiting embodiments andproperties of the present invention.

Example 1

A sheet of polyurethane (PU) open-cell foam was provided, with a densityof 0.022 g/cc. A silica precursor solution was formed by combiningmethyltriethoxysilane (MTES), tetraethoxyorthosilicate (TEOS), water,acid catalyst, and ethanol. A gelation catalyst solution was formed bycombining ethanol with dilute NH₃ in H₂O. The catalyst solution wascombined with the silica precursor solution to form a catalyzed silicaprecursor solution. The catalyzed silica solution was poured into thepolyurethane foam sheet. The composite material was allowed to gel, andthen was aged in a hexamethyldisilazane (HMDS) ethanolic solution. Thesolvent in the aged material was extracted under supercriticalconditions to generate a foam-reinforced aerogel composite. Theresulting aerogel-open cell polyurethane foam composites was flexible.

Example 2

A sheet of polyurethane (PU) open-cell foam is rolled into a preformroll and placed in a cylindrical walled container. A sheet ofmelamine-formaldehyde open-cell foam is rolled into a separate preformroll and placed in a separate cylindrical walled container. A silicaprecursor solution was formed by combining methyltriethoxysilane (MTES),tetraethoxyorthosilicate (TEOS), water, acid catalyst, and ethanol. Agelation catalyst solution was formed by combining ethanol with diluteNH₃ in H₂O. The catalyst solution was combined with the silica precursorsolution to form a catalyzed silica precursor solution. The resultingsolution was then poured over the open cell foam rolls previously placedin the separate containers. The materials were allowed to gel. Aftergelation, the resulting gel-foam composites were aged overnight in asealed bath of ethanol at 50° C. The solvent in the gels were removed bysupercritical CO₂ extraction to generate sheets of foam-reinforcedaerogel composite. The resulting aerogel-open cell polyurethane foamcomposite was flexible. The resulting aerogel-open cell melamine foamcomposite was flexible.

Example 3

A sheet of melamine-formaldehyde foam was provided. A silica precursorsolution was formed by combining methyltriethoxysilane (MTES),tetraethoxyorthosilicate (TEOS), water, acid catalyst, and ethanol. Agelation catalyst solution was formed by combining ethanol with diluteNH₃ in H₂O. The catalyst solution was combined with the silica precursorsolution to form a catalyzed silica precursor solution. The compositematerial was allowed to gel, and then was aged in a hexamethyldisilazane(HMDS) ethanolic. The solvent in the aged material was extracted undersupercritical conditions to generate a melamine-foam-reinforced aerogelcomposite. The resulting aerogel-melamine foam composites was flexible.

Example 4

Sheets of foam-reinforced aerogel composites from Example 1 and Example3 were provided. Multiple sheets of flexible facing material wereprovided, each comprising about 18% spandex and 82% nylon, with adensity of 0.3 g/cc. A first surface of each of the foam-reinforcedaerogel composite sheets was coated with an acrylic water based adhesive(3M Fastbond Pressure Sensitive Adhesive, 4224-NF clear or blue). Theadhesive was allowed to partially dry until tacky. A sheet of theflexible facing material was applied to each adhesive-coated surface ofthe foam-reinforced aerogel composites. Pressure was applied to thelaminate as the adhesive completed drying, thus forming a solid bondbetween the foam-reinforced aerogel composites and the flexible facinglayers. The lamination process was then repeated for the second surfaceof each foam-reinforced aerogel composite, thus forming a sandwichlaminate sheet comprising a base layer comprising a foam-reinforcedaerogel composite with flexible facing layers on each surface of thebase layer. FIG. 3 and FIG. 4 depict a sandwich laminate materialproduced in Example 4.

Example 5

Sheets of foam-reinforced aerogel composite from Example 1 was provided.Sheets of flexible facing material were provided, each comprising afluid-impermeable polyurethane. A first surface of the foam-reinforcedaerogel composite sheet was coated with a thermo-bonding polyethylenebased adhesive. A sheet of the flexible facing material was applied tothe coated surface of the foam-reinforced aerogel composite sheet.Pressure and heat was applied to the laminate as the adhesive completedbonding, thus forming a solid bond between the foam-reinforced aerogelcomposite and the flexible facing layer. The lamination process was thenrepeated for the second surface of the foam-reinforced aerogelcomposite, thus forming a sandwich laminate sheet comprising a baselayer comprising a foam-reinforced aerogel composite with flexiblefacing layers on each surface of the base layer. FIG. 5 depicts asandwich laminate material produced in Example 5.

Example 6

Sheets of foam-reinforced aerogel composite from Example 3 was provided.Sheets of flexible facing material were provided, each comprising about18% spandex and 82% nylon, with a density of 0.3 g/cc. A sheet offlexible facing spandex material was placed on each side of the sheet offoam-reinforced aerogel composite. An Ultrasonic Sewing Machine was usedto bond the laminate through patterned application of high-energyultrasonic energy through the layers of the laminate. The UltrasonicSewing process formed a sandwich laminate sheet comprising a base layercomprising a foam-reinforced aerogel composite with flexible facinglayers attached to each surface of the base layer, and with no adhesivematerial between the base layer and the facing layer. FIG. 6 and FIG. 7depict a sandwich laminate material produced in Example 6.

Example 7

Samples from Examples 4, 5 and 6 were provided. Each sample was testedfor density and thermal conductivity (TC) both before and after thelamination process. TC was measured at 37.5° C. in atmospheric pressure,and under a 2 psi load. The following Table 1 provides measurementresults:

TABLE 1 Thickness Density Sample Example Description (mm) (g/cc) TC(mW/m-K) 1a 1 Polyurethane foam; 2.32 0.164 15.0 unlaminated 1b 1, 4Polyurethane foam; 3.62 0.230 22.4 laminated w/ spandex 2a 3 Melaminefoam; 2.51 0.122 12.6 unlaminated 2b 3, 4 Melamine foam; 3.82 0.198 18.7laminated w/ spandex 3a 1 Polyurethane foam; 12.3 0.163 17.6 unlaminated3b 1, 5 Polyurethane foam; 12.9 0.187 18.4 laminated w/ polyurethane 4a3 Melamine foam; — 0.122 15.0 unlaminated 4b 3, 6 Melamine foam; — 0.17025.2 laminated w/ spandex; ultrasonic sewing

Example 8

The steps of Example 1 were repeated using a sheet of reticulatedpolyurethane foam as the reinforcing material, 12 mm in thickness. Thefoam-reinforced aerogel sheet was folded into a preformed shape andsecured with a band, as shown in FIG. 8. The folded sheet was placed inan oven and heated treated at a temperature of 150° C. for up to 3hours. The material was removed from the oven and allowed to cool. Thesecuring band was removed, and the heat-treated sheet was allowed topartially unfold. The resulting heat-treated sheet permanently retaineda semi-circular shape, as shown in FIG. 9.

Example 9

The steps of Example 1 were repeated using a sheet of reticulatedpolyurethane foam as the reinforcing material, 12 mm in thickness. Thefoam-reinforced aerogel sheet was folded into a preformed shape andsecured with a band, as shown in FIG. 8. The folded sheet was placed inan oven and heated treated at a temperature of 150° C. for up to 3hours. The material was removed from the oven and allowed to cool. Thesecuring band was removed, and the heat-treated sheet was allowed topartially unfold. The resulting heat-treated sheet permanently retaineda semi-circular shape, as shown in FIG. 9.

Example 10

Multiple heat-shaped aerogel composite sheets from Example 9 wereprovided. The heat-shaped sheets were laminated into a multilayerhalf-shell insulation laminate using an adhesive to bond layerstogether, as shown in FIG. 10. Two of these half-shell, pre-forminsulation laminates were combined around a pipe section and securedwith a band, thus forming an insulation sleeve fully encasing the outercircumference of the pipe section, as shown in FIG. 11.

Example 11

A sheet of polyurethane (PU) open-cell foam is provided. Two sheets offlexible facing material are provided, each comprising about 18% spandexand 82% nylon, with a density of 0.3 g/cc. A polyurethane compositeadhesive is applied to portions of a first surface of the foam sheet. Asheet of the flexible facing material is applied to theadhesive-modified surface of the foam sheet. Pressure is applied to thelaminate as the adhesive completes drying, thus forming a solid bondbetween the foam sheet and the flexible facing layer. The laminationprocess is then repeated for the second surface of the foam sheet, thusforming a sandwich laminate sheet comprising a base layer comprising afoam sheet with flexible facing layers attached to each surface of thebase layer.

Example 12

A sandwich laminate sheet from Example 11 is provided. The sandwichlaminate sheet is rolled into a preform roll; a spacer material isco-rolled with sandwich laminate sheet to provide spacing between thelayers of the roll. The roll is placed in a cylindrical walledcontainer. A silica precursor solution is formed by combining methyltriethoxysilane (MTES), tetraethoxy orthosilicate (TEOS), water, acidcatalyst, and ethanol. A gelation catalyst solution is formed bycombining ethanol with dilute NH₃ in H₂O. The catalyst solution iscombined with the silica precursor solution to form a catalyzed silicaprecursor solution. The resulting solution is then poured into thecontainer. The catalyzed silica precursor solution is allowed time toinfiltrate through the facing layers into the foam base layer of thesandwich laminate sheet, and the materials are allowed to gel. Aftergelation, the resulting gel-foam composites are aged overnight in asealed bath of ethanol at 50° C. The solvent in the gels is removed bysupercritical CO₂ extraction to generate sheets of laminated,foam-reinforced aerogel composite.

Example 13

A sandwich laminate sheet from Example 11 is provided. A silicaprecursor solution is formed by combining methyl triethoxysilane (MTES),tetraethoxy orthosilicate (TEOS), water, acid catalyst, and ethanol. Agelation catalyst solution is formed by combining ethanol with diluteNH₃ in H₂O. The catalyst solution is combined with the silica precursorsolution to form a catalyzed silica precursor solution. The sandwichlaminate sheet is fed onto a moving conveyor, and the resultingcatalyzed silica precursor solution is poured onto the top facing layerof the sandwich laminate sheet as it travels along the moving conveyor.The catalyzed silica precursor solution is allowed time to infiltratethrough the top facing layer into the foam base layer of the sandwichlaminate sheet, and the materials are allowed to gel. After gelation,the resulting sandwich laminate gel-foam composite sheet is rolled andplaced into cylindrical walled container; a spacer material is co-rolledwith composite sheet to provide spacing between the layers of the roll.The rolled composite sheet is aged overnight in a sealed bath of ethanolat 50° C. The solvent in the gels is removed by supercritical CO₂extraction to generate sheets of laminated, foam-reinforced aerogelcomposite.

Example 14

For Example 14, density was gravimetrically determined using a standardanalytical balance in conjunction with a volume determination inaccordance with the general teachings described in ASTM C303 and thermalconductivity was determined at a mean temperature of 37.8° C. at acompressive load of 2 PSI in accordance with the general teachingsdescribed in ASTM C518.

A continuous matrix of aerogel within a microporous scaffold was createdin the following manner. A 0.61 m width roll of 90 pores/inch (ppi)(35.4 pores/cm) reticulated polyester polyurethane foam, with a nominaldensity of 2.2 lb/ft³ (35.2 kg/m³) and about 0.080 inch in thickness (2mm) (RS090WHGR1, Crest Foam Industries Inc., division of INOAC,Moonachie, N.J.) was obtained.

A roll of expanded PTFE membrane (0.81 m) that had been subjected totemperatures above the crystalline melt temperature of PTFE andpossessing the following properties was obtained: average thickness of0.0137 mm, average density of 0.370 g/cc, average Frazier Number of 9.5,average Gurley Number of <1, average matrix tensile strength in thedirection of the fibrils of 222 MPa, average matrix tensile strength inthe direction orthogonal to the direction of the fibrils of 91 MPa, andpore size of 5.0 μm. This membrane was made generally in accordance withthe teachings of U.S. Pat. No. 5,814,405.

A polyurethane adhesive similar to those cited in U.S. Pat. No.4,532,316 was heated to a temperature sufficient to liquefy. Theadhesive was applied to the membrane in a dot pattern with an adhesivelaydown of about 40% by area via a gravure roll apparatus which had beenheated to about 115° C.

The adhesive coated side of the membrane was adhered to one side of thereticulated polyurethane foam by passing it through a nip, and theresulting laminate was collected on a spool. Another length of theadhesive coated membrane was applied to the opposite side of thereticulated foam in a similar manner to create a laminated construct.The laminated construct was spooled and allowed to cure at roomtemperature for 48 hours.

A requisite amount of a sol comprising hydrolyzed tetraethoxysilane andits derivatives and condensation catalyst, aqueous ammonium hydroxide,were combined and allowed to infiltrate the laminated construct. After asyneresis period of 3-30 minutes the gel/foam composite was subjected tofurther chemical aging, in which the wet gel composite was exposed to ahot ethanol solution of ammonium hydroxide and a hydrophobic agentcontaining various amounts of alkyl and silyl groups(hexamethyldisilazane). After aging, the foam/aerogel composite wastransferred to a cylindrical pressure vessel and was then dried usingsupercritical CO₂ extraction to remove the solvent. The composite wasthen treated with heat to remove any residual moisture content and/orvolatiles.

Three samples measuring approximately 20 cm by 20 cm were cut from thelaminate construct impregnated with aerogel. These samples weredetermined to have the following properties: average thickness of 1.61mm; average density of 0.179 g/cc; average thermal conductivity 13.9mW/mK. These samples demonstrated a high dust retention.

Example 15

For Example 15, density was gravimetrically determined using a standardanalytical balance in conjunction with a volume determination inaccordance with the general teachings described in ASTM C303 and thermalconductivity was determined at a mean temperature of 37.8° C. at acompressive load of 2 PSI in accordance with the general teachingsdescribed in ASTM C518.

A continuous matrix of aerogel within a microporous scaffold was createdin the following manner. Two different membranes of expandedpolyethylene (ePE) were used as scaffolds. Both scaffolds werecommercially available as Arioso™ composite membranes (Lydall) and were8.5×11 inches. Both materials had an average Gurley number of less than1 sec, and a pore size of 8.8 μm. These Arioso scaffolds contained ePEon one side of porous layer.

A requisite amount of a sol comprising hydrolyzed tetraethoxysilane andits derivatives and a condensation catalyst, aqueous ammonium hydroxide,were combined and allowed to infiltrate each membrane.

The membranes were determined to have the following properties beforeand after addition of the aerogel in Table 1. When testing thermalconductivity both samples were stacked and an average thermalconductivity was obtained as shown in Table 1. These materialsdemonstrated a high dust retention.

TABLE 2 Thickness Density Average Thermal Sample Initial Final InitialFinal Conductivity at 37.5° C. 1a 0.70 0.85 0.142 0.194 13.6 mW/m-K 1b0.47 0.50 0.132 0.171

Example 16

For Example 16, density was gravimetrically determined using a standardanalytical balance in conjunction with a volume determination inaccordance with the general teachings described in ASTM C303 and thermalconductivity was determined at a mean temperature of 37.8° C. at acompressive load of 2 PSI in accordance with the general teachingsdescribed in ASTM C518.

A continuous matrix of aerogel within a microporous scaffold was createdin the following manner. A nonwoven fabric comprising oxidizedpolyacrylonitrile (OPAN) fiber with an areal density, 0.01-0.03 g/cm²was obtained.

A roll of expanded PTFE membrane (0.81 m) that had been subjected totemperatures above the crystalline melt temperature of PTFE andpossessing the following properties was obtained: average thickness of0.032 mm, average density of 0.587 g/cc, pore size of 0.47 μm, averageGurley number of 8.9 sec, average matrix tensile strength in thedirection of the fibrils of 88 MPa, and average matrix tensile strengthin the direction orthogonal to the direction of the fibrils of 35 MPa.This membrane was made generally in accordance with the teachings ofU.S. Pat. No. 3,953,566.

A polyurethane adhesive similar to those cited in U.S. Pat. No.4,532,316 was heated to a temperature sufficient to liquefy. Theadhesive was applied to the membrane in a dot pattern with an adhesivelaydown of about 40% by area via a gravure roll apparatus which had beenheated to about 115° C.

The adhesive coated side of the membrane was adhered to one side of thereticulated polyurethane foam by passing it through a nip, and theresulting laminate was collected on a spool. Another length of theadhesive coated membrane was applied to the opposite side of thereticulated foam in a similar manner to create a laminated construct.The laminated construct was spooled and allowed to cure at roomtemperature for 48 hours.

A requisite amount of a sol comprising hydrolyzed tetraethoxysilane andits derivatives and a condensation catalyst, aqueous ammonium hydroxide,were combined and allowed to infiltrate the laminated construct. After asyneresis period of 3-30 minutes the gel/foam composite was subjected tofurther chemical aging, in which the wet gel composite was exposed to ahot ethanol solution of ammonium hydroxide and a hydrophobic agentcontaining various amounts of alkyl and silyl groups(hexamethyldisilazane). After aging, the foam/aerogel composite wastransferred to a cylindrical pressure vessel and was then dried usingsupercritical CO² extraction to remove the solvent. The composite wasthen treated with heat to remove any residual moisture content and/orvolatiles.

Ten samples measuring approximately 10 cm by 10 cm were cut from thelaminate construct impregnated with aerogel. These samples weredetermined to have the following properties: average thickness of 2.29mm; average density of 0.0243 g/cc; average thermal conductivity 17.4mW/mK. These samples demonstrated a high dust retention.

As used herein, the conjunction “and” is intended to be inclusive andthe conjunction “or” is not intended to be exclusive unless otherwiseindicated. For example, the phrase “or, alternatively” is intended to beexclusive.

The use of the terms “a”, “an”, “the”, or similar referents in thecontext of describing the invention (especially in the context of theclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.

The terms “comprising,” “having,” “including,” and “containing” are tobe construed as open-ended terms (i.e., meaning “including, but notlimited to,”) unless otherwise noted.

As used herein, the term “about” refers to a degree of deviation typicalfor a particular property, composition, amount, value or parameter asidentified; such as deviations based on experimental errors, measurementerrors, approximation errors, calculation errors, standard deviationsfrom a mean value, routine minor adjustments, and so forth.

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein.

All methods described herein can be performed in any suitable orderunless otherwise indicated herein or otherwise clearly contradicted bycontext. The use of any and all examples, or exemplary language (e.g.,“such as”, “for example”) provided herein, is intended merely to betterilluminate the invention and does not pose a limitation on the scope ofthe invention unless otherwise claimed.

What is claimed is:
 1. An aerogel composite comprising: at least onebase layer having a top surface and a bottom surface, the base layercomprising a reinforced aerogel composition which comprises areinforcement material and a monolithic aerogel framework; a firstfacing layer comprising a first facing material permanently attached tothe top surface of the base layer via a first adhesive; and a secondfacing layer comprising a second facing material permanently attached tothe bottom surface of the base layer via a second adhesive; wherein atleast a portion of the monolithic aerogel framework of the base layerextends into at least a portion of both the first facing layer and thesecond facing layer; wherein the first facing material and the secondfacing material each consist essentially of fluoropolymer material; andwherein the reinforcement material and the fluoropolymer material aredifferent.
 2. The aerogel composite of claim 1, wherein thereinforcement material comprises a foam reinforcement material.
 3. Theaerogel composite of claim 1, wherein each of the first adhesive and thesecond adhesive is selected from the group consisting of: an aerosoladhesive, a urethane-based adhesive, an acrylate adhesive, a hot meltadhesive, an epoxy, a rubber resin adhesive; a polyurethane compositeadhesive, and any combinations thereof.
 4. The aerogel composite ofclaim 1, wherein the first facing layer and second facing layer eachcomprise a fluid-permeable facing material.
 5. The aerogel composite ofclaim 1, wherein the composite material has a thermal conductivitybetween 18.0 mW/m-K and 40.0 mW/m-K.
 6. The aerogel composite of claim1, wherein the first adhesive and the second adhesive are the same. 7.The aerogel composite of claim 1, wherein the first adhesive and thesecond adhesive are different.